1. Field of the Invention
The present invention relates to a novel substrate for manufacturing single crystal thin films.
2. Description of Prior Art
Recently, there has been an increasing demand for large area thin films and single crystals in the form of a thin plate for applications relating to solar cells, imaging sensors, ultra-large scale integrated circuits and electroluminescence displays, etc. In the semi-conductors and dielectric materials which are currently employed as electronic circuit elements and display devices, a large single crystal is once grown from a seed crystal so as to be formed into a thin-plate configuration by sawing for practical uses. Concerning Si crystal which has been widely employed as an electronic circuit element, functional devices such as transistors, diodes, etc. are fabricated in a position only 10 to 20 .mu.m deep from the surface of the substrate. However, the actual thickness of the substrate is in the range of 300 to 400 .mu.m for convenience in the processing steps. This means that more than 95% of the thickness of the expensive single crystal substrate is used merely for supporting purpose, and a thickness only less than 5% is alloted for the functional devices.
Accordingly, the object of the present invention is to provide an improved substrate for manufacturing single crystal thin films, which is capable of growing single crystal thin films of large area at high purity with the thickness necessary for functional devices, etc.